The time may come where you will have to burn both a Blu-Ray disc for your family, and an HD-DVD disc for your boss who got hurried out and bought that HD-DVD player just so he can show off to all of you who waited for the format war outcome. Besides, while the HD format war is over, there are still over 1.3 million HD-DVD devices out there. I have modified some HD authoring methods found on the net in a way that 80% of the work to be done is the same for both formats, and with the rest 20% of the work only taking an additional 10 minutes for each format to be muxed and burned. Blu-Ray method is here, and the HD-DVD method is here (methods are identical up to step #7). Not only that, but you won't even need an HD burner, as these methods exercise plain DVD-R discs and they are using freeware tools.

I appreciate the time and effort it took for you to create the tutorial.
Given the large number of creatives that do work on other platforms (ie, OSX), could you point us in a direction or is there a source for us to research.
I realize that DVD Studio will author HD-DVD (Apple needs to get an update out I think), but are there other applications that you know of.